Valves, such as a butterfly valve, are typically installed in a fluid system, such as a water system. For example, a valve can be useful in temporarily preventing flow from one portion of a fluid system to another portion of the fluid system. A valve that does not seal effectively or that does not continue to seal effectively after repeated opening and closing, however, can result in costly repairs, unnecessarily frequent maintenance, and sometimes additional costs resulting from the valve's failure to completely stop the flow of fluid through the fluid system.